Python Decorators Advanced

Advanced Python Decorators

Implementing advanced Python decorators — from parameterized decorators through class decorators, decorators with arguments, and stacked patterns.

When to Use

• Building reusable cross-cutting concerns
• Implementing caching, retry, timing decorators
• Building DSL-like APIs with decorators

Decorator Patterns

from functools import wraps
import time

def retry(max_attempts=3, delay=1):
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            for i in range(max_attempts):
                try: return func(*args, **kwargs)
                except Exception as e:
                    if i == max_attempts - 1: raise
                    time.sleep(delay)
            return None
        return wrapper
    return decorator

def timer(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        start = time.time()
        result = func(*args, **kwargs)
        print(f"{func.__name__}: {time.time()-start:.3f}s")
        return result
    return wrapper

Verification Checklist

• @wraps used to preserve metadata
• Decorator factory with arguments pattern
• Stacking decorators in correct order
• Class-based decorators with call
• Async decorator support